This invention relates to improvements in the design of shoe and lining assemblies for use in disc brakes.
Disc brakes are utilized in many heavy vehicle braking systems. Typically, an air actuator is driven to rotate an eccentric piston actuator. Typically there are two spaced pistons. The pistons are actuated to drive a disc brake shoe and lining assembly into contact with a rotor. The rotor rotates with the wheel, and when the shoe and lining assembly is brought into contact with the rotor, it retards rotation of the wheel.
Modern braking systems are quite complex and carry a number of relatively moving parts. The brake assembly, including its several components, must fit within the envelope of the wheel for which the brake is associated. As such, there are competing demands on the brake designer.
With regard to the shoe and lining assemblies, it is desirable to have the pistons be as close to a centroid of one-half of the shoe and lining assembly as is possible. However, existing disc brake systems have not fully achieved this goal.
In disclosed embodiments of this invention, the shape and dimensions of a saddle or seat for the shoe and lining assembly is designed to result in pistons which are centered close to a true centroid of one-half of the shoe and lining assembly. The force from the pistons is thus distributed as evenly as possible across the shoe and lining assembly. In this way, the braking force applied to the shoe and lining assembly is applied as evenly as possible across the entire friction surface, and braking efficiency is increased.
The present invention evaluates the competing space challenges of having sufficient size for the housing structure, actuation structure, supporting structure, and shoe and lining assemblies. In addition, the present invention evaluates the complete design to result in piston centroids which are as close as possible to a centroid of one-half of the shoe and lining assembly.
While the invention is claimed as a combination of shapes and dimensions of the shoe and lining assemblies, in fact a good deal of the inventive effort is in the creation of the surrounding brake which results in the particular shape and dimensions for the shoe and lining assembly:
These and other features of the present invention are best understood from the following specification and drawings, of which the following is a brief description.